With the reduction of geometry sizes and the increase of aspect ratios, the ability to achieve a uniform Cu metallization becomes increasingly difficult. With the down scaling of the interconnect technology, in sub-30 nm line width regions, the resistivity of traditional copper (Cu) interconnects is expected to dramatically increase. This resistivity increase is mainly associated with the increased grain boundary and surface scattering of copper (Cu). Therefore, a copper (Cu) replacements needs to be found for the next generation of interconnects.
Metal is a promising alternative as a potential replacement for Cu as interconnect metal due to the slow resistivity increase in dimensions below 30 nm. However, the suitability of metal is mainly determined by its filling ability and the impact of finite size effects on its electrical and reliability properties that should be on the same order as narrow copper lines.
However, current methods for obtaining a low resistive metal phase are not suitable to be integrated in the fabrication of narrow line interconnect structures in semiconductor devices.